What is the sum of the two solutions to the equation $54-15x-x^2=0$?
Explanation: If the two solutions are $r$ and $s$, then the left-hand side of the equation may be factored as $-(x-r)(x-s)$. When multiplied out, this expression takes the form $-x^2+(r+s)x-rs$.  Therefore, $r+s$ is the coefficient of $x$ in the equation, namely $\boxed{-15}$.